In order to meet the increasing demands for broadband wireless access, mobile service providers are now deploying distributed antenna multiple input multiple output (MIMO) systems. MIMO systems typically use the same radio frequency spectrum for several antennas which work together to cooperatively detect the signals. This enhances reach and capacity of wireless signals at the cost of increased signal processing complexity. Multicore fibers have recently gained considerable attention within the telecom industry as a way of reducing the footprint of optical data links.
In traditional radio-over-fiber/wireless-over-fiber systems a laser is driven by the signal received from the antenna, and the optical signal is transmitted over a fiber link to the central station. For the downlink, the radio-frequency signal is generated at the central station and transmitted over the fiber link to the antenna station, where it is photodetected and amplified before being fed to the antenna. Usually, each antenna will be connected to the central station via a duplex fiber link.
Optical communication systems incorporating a MIMO configuration employing one or more multicore fibers in the backhaul link are disclosed in the prior art. US 2012/163801 discloses an optical fiber communication system enabling achievement of a large-capacity optical communication with a small number of optical fibers. The communication system includes an optical transmitter transmitting a plurality of optical signals in parallel through the respective cores of a multicore fiber, and an optical receiver receiving the optical signals output in parallel from the respective cores of the multicore fiber. The optical transmitter and the optical receiver thereby essentially form a MIMO optical communication employing a multicore fiber.